Mostly because we'd basically have to quadruple every setting that includes the ProRes Codec. So for every frame size and rate, we'd need to essentially add 3 more preset per. As you can see the Blackmagic List is already long. No technical reason, just a practical reason.

Easiest thing to is to duplicate the default prores setting and change the codec as Juan mentioned, then save it out again. Do this for the framesizes and rates you use.